Bioinspired Structural Color Patterns Derived from 1D Photonic Crystals with High Saturation and Brightness for Double Anti-Counterfeiting Decoration
Wei Ma, Yusheng Kou, Peng Zhao, Shufen Zhang
Abstract
Imitating the butterfly wing scale with a layer-by-layer structure and angle-dependent property, we present a facile method for the fabrication of flexible, transferable, and multilayered one-dimensional photonic crystal (1D PC) patterns with high color brightness and saturation for anticounterfeiting decoration. The PCs with a thickness less than 1 μm are assembled by alternate spin-coating poly(methyl methacrylate) (PMMA) nanoparticles and titania ones on plane substrates, and their color shade and reflectivity are adjusted by modulating PMMA concentration and stack number, respectively. As the particle-based PMMA layer shows weak binding force with both hydrophilic and hydrophobic substrates, when a certain external force from pressure-sensitive adhesive is exerted on the PC, the thin colorful film can be directly peeled off. With a patterned double-sided adhesive tape, the PCs with various structural color patterns can be transferred and strongly bonded to other flexible or curved substrates. Owing to the dark color of the adhesive, transmitted light is absorbed, and backscattering is effectively lowered to obtain very brilliant structural colors. The transferred PC patterns with beautiful colors show strong angle dependence and environmental stimulus responses because of the sensitive PMMA material and textural pores existing in the PCs. With this method, double anticounterfeiting with higher security and decorative effect is achieved with simple PCs for various product packages.